CN107287631A - Microelectrode and preparation method and application - Google Patents

Abstract

The invention discloses a microelectrode, its preparation method and application. The microelectrode of the present invention includes a substrate and a microelectrode unit arranged on the substrate, a three-dimensional platinum nano-layer is also combined on the outer surface of the micro-electrode unit, and a charge storage and injection is also combined on the outer surface of the three-dimensional platinum nano-layer An enhancement layer, wherein the three-dimensional platinum nano-layer contains a suede surface distributed with several platinum nanocones or platinum nanoflowers, and the charge storage and injection enhancement layer is combined on the suede surface. The microelectrode of the present invention has a large surface area, and effectively reduces the impedance of the microelectrode, increases the electrochemical properties such as charge storage capacity and charge injection capacity, and ensures that the microelectrode of the present invention has good biocompatibility and such as mechanical stability and electrochemical stability. and other long-term stability, thereby improving the electrical stimulation efficiency of the microelectrode of the present invention. Each step of the preparation method of the invention can be effectively controlled, thereby ensuring stable performance of the prepared microelectrode, high efficiency, and industrial production.

Description

Microelectrode and its preparation method and application

technical field

The invention belongs to the technical field of biomedical equipment, and in particular relates to a microelectrode and its preparation method and application.

Background technique

As one of the most important implantable microdevices, nerve stimulation/recording electrodes are used to stimulate nerve tissue or record nerve electrical signals, and are widely used in life science fields such as neurophysiology and brain science research, such as observing neural behavior or treating blindness and deafness , Parkinson's disease, and other neurological disorders. In order to reduce surgical trauma and provide higher electrical stimulation or recording efficiency to clinics, nerve stimulation/recording electrodes are developing toward integration and miniaturization—microelectrode arrays. However, the size reduction of microelectrodes brings performance problems such as increased electrode impedance and reduced capacitance, which seriously reduces the safe stimulation efficiency of microelectrodes. At present, without increasing the geometric size of the electrode, the effective surface area of the electrode is mainly increased by surface modification, and the mechanical and electrochemical properties of the electrode are improved.

At present, the above purpose is mainly achieved by depositing rough porous materials on the surface of microelectrodes. Several typical materials can be summarized as follows: 1. Platinum black is deposited on the surface of the electrode. The coating has the advantage of being loose and porous, and can significantly reduce the electrochemical impedance of the electrode. However, the platinum black coating contains toxic additives such as lead, which seriously affects its application. Safe; 2. Deposit a layer of rough or irregular platinum coating on the surface of the electrode to replace platinum black. Although the coating has a certain roughness, its electrochemical impedance is still high and its charge storage capacity is low, which limits its stimulation. Efficiency; 3. The combination of conductive polymer and carbon nanotubes can improve its charge storage and injection capabilities to a certain extent, but the stability is poor, and it is easy to fall off during ultrasonic or electrochemical stimulation; 4. In addition, boron doped The impurity diamond coating has a certain effect on improving the electrochemical performance, but its high time and economic cost are not conducive to its clinical application.

Therefore, the coatings obtained by the current microelectrode surface modification methods cannot meet the index requirements of low impedance, high charge storage capacity, high charge injection capacity and long-term stability. How to reduce the microelectrode impedance, improve charge storage capacity and high charge injection capacity and Work stability is a technical problem that the technical field has been trying to solve.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, to provide a microelectrode and a preparation method thereof, to solve the technical problems of high impedance, charge storage capacity, charge injection capacity and unsatisfactory work stability of the existing microelectrode .

In order to achieve the purpose of the above invention, one aspect of the present invention provides a microelectrode. The microelectrode includes a substrate and a microelectrode unit arranged on the substrate, a three-dimensional platinum nanolayer is also combined on the outer surface of the microelectrode unit, and a charge storage and injection is also combined on the outer surface of the three-dimensional platinum nanolayer An enhancement layer, wherein the three-dimensional platinum nano-layer contains a suede surface distributed with several platinum nanocones or platinum nanoflowers, and the charge storage and injection enhancement layer is combined on the suede surface.

Another aspect of the present invention provides a method for preparing a microelectrode. The preparation method of described microelectrode comprises the steps:

A three-dimensional platinum nanolayer and a charge storage and injection enhancement layer are sequentially prepared on the outer surface of the microelectrode unit arranged on the substrate; wherein, the three-dimensional platinum nanolayer contains a suede surface distributed with several platinum nanocones or platinum nanoflowers, and the The charge storage and injection enhancement layer is combined on the suede surface.

Another aspect of the present invention provides an application of the microelectrode of the present invention in sensors, wearable devices or implantable devices.

Compared with the prior art, the microelectrode of the present invention sequentially arranges a three-dimensional platinum nanolayer and a charge storage and injection enhancement layer on the outer surface of the microelectrode unit, and through the synergistic effect of the added two functional layer structures, the microelectrode of the present invention has a large The surface area of the microelectrode can effectively reduce the impedance of the microelectrode, increase the electrochemical performance of the charge storage capacity and the charge injection ability, and ensure that the microelectrode of the present invention has good biocompatibility and long-term stability such as mechanical stability and electrochemical stability, thereby Improve the electrical stimulation efficiency of the microelectrode of the present invention. Wherein, the three-dimensional platinum nanolayer structure plays the role of the middle adhesion layer, which greatly increases the effective surface area of the microelectrode of the present invention, and simultaneously increases the binding force between the charge storage and injection enhancement layer and the outer surface of the microelectrode unit; charge storage The injection-enhancing layer effectively improves the charge storage capability, charge injection capability and biocompatibility.

The preparation method of the microelectrode of the present invention sequentially prepares a three-dimensional platinum nanolayer and a charge storage and injection enhancement layer on the outer surface of the microelectrode unit, and makes the prepared three-dimensional platinum nanolayer contain a suede surface distributed with several platinum nanocones or platinum nanoflowers , and the charge storage and injection enhancement layer is combined on the suede surface, so that the microelectrode has a large surface area, and effectively reduces the microelectrode impedance, increases the electrochemical performance of the charge storage capacity and charge injection capacity, and ensures this The inventive microelectrode has good biocompatibility and long-term stability such as mechanical stability and electrochemical stability, thereby improving the electrical stimulation efficiency of the inventive microelectrode. In addition, each step of the preparation method of the present invention can be effectively controlled, thereby ensuring stable performance of the prepared microelectrode, high efficiency, and industrial production.

It is precisely because the microelectrode of the present invention has electrochemical properties such as low impedance, high charge storage capacity and charge injection capacity, good working stability, and high electrical stimulation efficiency. Therefore, the microelectrode of the present invention can be used in sensors, wearable devices or Implantable devices such as in vivo pH measurement, ion analysis, neural prosthesis, nerve stimulation/recording, etc., so as to improve the sensitivity and accuracy of the corresponding devices.

Description of drawings

Fig. 1 is the microelectrode structure schematic diagram of the embodiment of the present invention;

Fig. 2 is the enlarged sectional view of the A part single microelectrode unit of microelectrode shown in Fig. 1;

Fig. 3 is the SEM picture that contains the platinum nano cone suede of three-dimensional platinum nanolayer; Wherein, Fig. b is the partial enlarged view of Fig. a;

Fig. 4 is the suede SEM image of the outer surface of the composite functional layer composed of a three-dimensional platinum nanolayer and a charge storage and injection enhancement layer;

Fig. 5 is the SEM picture of the iridium oxide layer 4 of the microelectrode that comparative example 1 provides

Fig. 6 is the impedance performance curve figure of the microelectrode that embodiment 1 and comparative examples 1-3 provide; Wherein, curve a is the impedance performance curve of comparative example 3, and curve b is the impedance performance curve of comparative example 2, and curve c is the impedance performance curve of comparative example 2. The impedance performance curve of ratio 1, curve d is the impedance performance curve of embodiment 1;

Fig. 7 is the cyclic voltammetry (CV) curve figure of the microelectrode that embodiment 1 and comparative examples 1-3 provide; Wherein, curve a is the CV curve of comparative example 3, and curve b is the CV curve of comparative example 2, and curve c Be the CV curve of comparative example 1, curve d is the CV curve of embodiment 1;

Fig. 8 is a graph of cyclic voltammetry (CV) curves of the microelectrode provided in Example 1 before and after electrical stimulation at 0h, 24h, 72h, and 96h.

detailed description

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments and accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

In one aspect, embodiments of the present invention provide a microelectrode with good biocompatibility and long-term stability such as mechanical stability and electrochemical stability. The microelectrode structure of the present invention is shown in Figures 1-4, and has the necessary components of a conventional microelectrode, such as a substrate 1 and a microelectrode unit 2 disposed on the substrate 1, as shown in Figure 1 . A three-dimensional platinum nanolayer 3 is also combined on the outer surface of the microelectrode unit 2, and a charge storage and injection enhancement layer 4 is also combined on the outer surface of the three-dimensional platinum nanolayer, as shown in FIG. 2 .

Wherein, the matrix 1 contained in the microelectrode is used as the carrier of the microelectrode unit 2, therefore, the matrix 1 can be a conventional matrix contained in a conventional microelectrode with biocompatibility.

The micro-electrode unit 2 included in the above-mentioned micro-electrode is arranged on the substrate 1. In addition, the micro-electrode unit 2 may be composed of one or more (more than two) single electrodes. When the microelectrode unit 2 is composed of multiple single electrodes, the microelectrode unit 2 is a microelectrode array unit. In addition, according to the shape, the microelectrode unit 2 (that is, a single electrode) is a disc electrode, a ring electrode, a cylindrical electrode, a spherical electrode, a semi-spherical electrode, a strip electrode, an array electrode, and an interdigitated electrode. any kind. Secondly, the size and material of the microelectrode unit 2 (that is, a single electrode) can be the conventional size and material of a single electrode contained in a conventional microelectrode. In a specific embodiment, the material of the microelectrode unit 2 is a platinum electrode unit 2 .

The three-dimensional platinum nanolayer 3 contained in the microelectrode is combined on the surface of the microelectrode unit 2, and when the microelectrode unit 2 contains multiple single electrodes, the three-dimensional platinum nanolayer 3 is combined on the surface of each single electrode. The way of combining the three-dimensional platinum nano-layer 3 on the surface of the micro-electrode unit 2 may be but not limited to electrodeposition.

In one embodiment, the above-mentioned three-dimensional platinum nanolayer 3 includes a suede surface 31 distributed with several platinum nanocones or platinum nanoflowers. Wherein, the suede surface 31 of the platinum nanocone is as shown in FIG. 3 . Due to the material properties of the three-dimensional platinum nano-layer 3 , it acts as an intermediate adhesion layer between the charge storage and injection enhancement layer 4 and the micro-electrode unit 2 . In addition, the three-dimensional structure of the three-dimensional platinum nanolayer 3, especially the textured surface 31 structure containing several platinum nanocones or platinum nanoflowers, effectively increases the charge storage capacity of the three-dimensional platinum nanolayer 3, especially the textured surface 31. The area in contact with the injection enhancement layer 4, that is, the three-dimensional platinum nanolayer 3, especially the textured surface 31, provides a large surface area to accommodate the charge storage and injection enhancement layer 4, thereby effectively preventing the charge storage and injection enhancement layer 4 from being too large during the preparation process. dense; on the other hand, the three-dimensional platinum nanolayer 3, especially the suede 31 structure, can effectively improve the bonding force between the charge storage and injection enhancement layer 4 and the microelectrode unit 2, thereby improving the structure of the microelectrode unit 2 and the three-dimensional platinum nanolayer. 3 and the charge storage and injection enhancement layer 4 constitute the stability of the overall structure of the microelectrode unit and the long-term stability of the working performance.

In a further embodiment, the height of the platinum nanocones or platinum nanoflowers on the suede 31 contained in the three-dimensional platinum nanolayer 3 is 50nm-800nm, and the diameter of the bottom is 50nm-500nm. In another embodiment, the distribution density of the platinum nanocones or platinum nanoflowers is 25-400/μm ² . By controlling the size and density of the platinum nanocones or platinum nanoflowers that constitute the suede 31, the quality of the charge storage and injection enhancement layer 4 is improved, and at the same time, the microelectrode unit 2, the three-dimensional platinum nanolayer 3 and the charge storage and injection enhancement layer are improved. The injection enhancement layer 4 constitutes the stability of the overall structure of the microelectrode unit and the long-term stability of the working performance.

The charge storage and injection enhancement layer 4 contained in the above-mentioned microelectrode is combined on the suede 31 of the three-dimensional platinum nano-layer 3, thereby effectively improving the charge storage capacity and charge injection capacity, and reducing the three-dimensional platinum nano-layer 3 and the charge storage and injection enhancement layer. 4 The impedance of the composite functional layer formed. In addition, the charge storage and injection enhancement layer 4 is formed along the structure of the textured surface 31 of the three-dimensional platinum nano-layer 3 , that is, the outer surface of the charge storage and injection enhancement layer 4 is basically the same as the structure shape of the textured surface 31 . Specifically, the charge storage and injection enhancement layer 4 is combined on the outer surface of the platinum nanocone or platinum nanoflower that constitutes the textured surface 31, and the specific three-dimensional platinum nanolayer 3 and the charge storage and injection enhancement layer 4 form a composite function The outer surface of the layer is shown in Figure 4. Therefore, in one embodiment, the thickness of the charge storage and injection enhancement layer 4 is 5 nm-600 nm. In another embodiment, the material of the charge storage and injection enhancement layer 4 is iridium oxide or conductive polymer. In a specific embodiment, when the material of the charge storage and injection enhancement layer is iridium oxide, the iridium oxide is combined on the suede 31 in the form of nanoparticles to form the charge storage and injection enhancement layer 4; the charge storage and injection enhancement layer 4 When the material is a conductive polymer, the conductive polymer is at least one of polypyrrole, polyaniline, polythiophene, polythiophene derivatives, and the like. By controlling and optimizing the thickness, size and material of the charge storage and injection enhancement layer 4, the microelectrode impedance is further reduced, the bonding strength of the charge storage and injection enhancement layer 4 is improved, and the charge storage and charge injection capabilities are improved.

Therefore, in the above-mentioned microelectrode, the composite functional layer composed of the three-dimensional platinum nanolayer 3 and the charge storage and injection enhancement layer 4 is used to modify the outer surface of the microelectrode unit 2, which endows the microelectrode in the above-mentioned embodiments with a large Surface area, and effectively reduce the electrochemical performance of microelectrode impedance, increase charge storage capacity and charge injection ability, ensure that the above microelectrodes have good biocompatibility and long-term stability such as mechanical stability and electrochemical stability, thereby improving the above-mentioned Electrical stimulation efficiency of microelectrodes.

Of course, the microelectrodes in the above embodiments include other necessary components besides the microelectrode unit 2 and the base 1 for supporting the microelectrode unit 2 . These other necessary components can be different according to different types of microelectrodes, and these other necessary components can also be conventional structures of conventional microelectrodes with biocompatibility.

On the other hand, the embodiment of the present invention also provides a method for preparing the above-mentioned microelectrodes. In combination with the microelectrode structure shown in Figures 1-4, the microelectrode preparation method described above includes the following steps:

A three-dimensional platinum nano-layer 3 and a charge storage and injection enhancement layer 4 are sequentially prepared on the outer surface of the micro-electrode unit 2 arranged on the substrate 1 .

Wherein, the three-dimensional platinum nanolayer 3 prepared on the outer surface of the microelectrode unit 2 has a suede 31 containing a number of platinum nanocones or platinum nanoflowers distributed, and the suede 31 is away from the outer surface of the microelectrode unit 2, that is, The textured surface 31 is combined with the charge storage and injection enhancement layer 4 .

In one embodiment, the preparation method of the three-dimensional platinum nanolayer 3 containing the suede 31 distributed with several platinum nanocones or platinum nanoflowers is as follows:

The plating solution containing the composite platinum salt is deposited on the outer surface of the micro-electrode unit with the three-dimensional platinum nano-layer 3 containing the suede 31 by means of constant potential deposition, constant current deposition, or pulse voltage deposition.

Specifically, when the three-dimensional platinum nano-layer 3 is prepared by constant potential deposition, the voltage of the constant potential deposition is -0.35V～-0.75V;

When the three-dimensional platinum nano-layer 3 is prepared by constant current deposition, the current of the constant current deposition is -0.25μA～-1.75μA;

When pulse voltage deposition is used to prepare the three-dimensional platinum nano-layer 3 , the voltage of the pulse deposition is -0.35V～-0.75V, and the on-off ratio is (2ms-100ms):(200ms-1000ms).

Regardless of which method in constant potential deposition, constant current deposition, and pulse voltage deposition is used to prepare the three-dimensional platinum nanolayer 3, the deposition time of any one of the constant potential deposition, constant current deposition, and pulse voltage deposition is preferably 5 to 60 minutes. , the pH of the plating solution ≥ 7; in addition, no matter which method is used to prepare the three-dimensional platinum nano-layer 3, the platinum salt in the plating solution containing the composite platinum salt includes platinum chloride, ammonium hexachloroplatinate, hexachloroplatinum Potassium chloride, sodium hexachloroplatinate, chloroplatinic acid, platinum nitrate, platinum sulfate, potassium tetrachloroplatinate, ammonium tetrachloroplatinate; specifically, the mass ratio is (0.5-25): (0.5 -25) the compound salt of sodium chloroplatinate and ammonium chloroplatinate. In one embodiment, the pH of the plating solution containing the complex platinum salt can be adjusted, but not only, with phosphate, for example, the phosphate is a buffer composed of disodium hydrogen phosphate and sodium dihydrogen phosphate complex salt.

In a further embodiment, organic or inorganic ammonium salt additives can also be added to the above-mentioned plating solution containing the composite platinum salt. Specifically, the total mass of the above-mentioned plating solution containing the composite platinum salt is 100%. The content is 1-50%, and the content of the organic or inorganic ammonium salt additive is 0-20%. Wherein, the composite platinum salt may contain sodium chloroplatinate and ammonium chloroplatinate at a mass concentration of 0.5-25% and ammonium chloroplatinate at a mass concentration of 0.5-25%, and the content of the additive is 0-20%. In addition, the additive may be one of organic or inorganic ammonium salts such as ethylenediamine dihydrochloride, ammonium chloride, ammonium sulfate, and ammonium nitrate.

By controlling the parameters of the method for preparing the three-dimensional platinum nano-layer 3, the three-dimensional platinum nano-layer 3 generated by the deposition has a three-dimensional structure with a large surface area, preferably with a suede surface 31 containing several platinum nano-cones or platinum nano-flowers distributed. , it is more preferred to have the textured surface 31 that contains some platinum nano cones distributed, and control parameters such as the height and density of platinum nano cones or platinum nano flowers, so that the three-dimensional platinum nano layer 3 has a large surface area, and improves Charge storage and injection enhance the performance of layer 4 .

In one embodiment, the preparation method of the above-mentioned charge storage and injection enhancement layer 4 is as follows:

Depositing an iridium oxide layer on the suede 31 of the above-mentioned three-dimensional platinum nano-layer 3 by means of constant potential deposition, constant current deposition, pulse voltage deposition, pulse current deposition, and cyclic voltammetry deposition in the plating solution containing iridium salt; or The conductive polymer solution is deposited on the suede surface 31 of the above-mentioned three-dimensional platinum nano-layer 3 to form a conductive polymer layer.

Specifically, when the iridium oxide layer is prepared by constant potential deposition, the voltage level of the constant potential deposition is 0.35V-0.65V;

When the iridium oxide layer is prepared by constant current deposition, the current of the constant current deposition is 0.05 μA to 1.5 μA;

When the iridium oxide layer is prepared by pulse deposition, the voltage of the pulse deposition is 0.35V～0.65V, and the on-off ratio is (2ms-100ms):(200ms-1000ms);

When the iridium oxide layer is prepared by cyclic voltammetry deposition, the cyclic voltammetry deposition voltage is 0.01V-0.8V, and the number of cycles is 20-600 cycles;

Regardless of which method of constant potential deposition, constant current deposition, pulse voltage deposition, pulse current deposition, and cyclic voltammetry deposition is used to prepare the charge storage and injection enhancement layer 4, the constant potential deposition, constant current deposition, and pulse voltage deposition , pulse current deposition, and cyclic voltammetry deposition, the preferred deposition time is 5-60 minutes, and the pH of the plating solution is greater than or equal to 10. In one embodiment, the pH of the iridium-containing salt bath can be adjusted, but not only, with weak acid and strong alkali salts, such as sodium carbonate, potassium carbonate, sodium acetate, sodium bicarbonate, sodium hypochlorite, and the like.

In addition, no matter which method is used to prepare the charge storage and injection enhancement layer 4, the iridium salt in the above-mentioned iridium salt-containing plating solution includes iridium chloride, chloroiridic acid, ammonium hexachloroiridate, potassium hexachloroiridate, At least one of iridium salts such as sodium hexachloroiridate. In a further embodiment, the above-mentioned plating solution containing iridium salt may also contain a weak acid or one or both of an oxidizing agent and a weak acid. In one embodiment, based on the total mass of the above-mentioned iridium salt-containing plating solution as 100%, the content of the iridium salt is 0.5-50%, the content of the oxidant is 0-10%, and the content of the weak acid is 0.1-10%; In a specific embodiment, the oxidant is at least one of hydrogen peroxide, sodium peroxide, potassium peroxide, oxygen, ozone, etc., and the weak acid is oxalic acid, citric acid, carbonic acid, acetic acid, formic acid, benzoic acid, etc. at least one of the

When the conductive polymer solution is deposited on the suede 31 of the above-mentioned three-dimensional platinum nano-layer 3 to form the conductive polymer layer, the conductive polymer is at least one of polypyrrole, polyaniline, polythiophene, polythiophene derivatives, etc. One, the thickness of the conductive polymer layer is 5nm-600nm. Wherein, the concentration of the conductive polymer solution can be any concentration as long as it is favorable for deposition to form the conductive polymer layer.

By controlling the parameters of the above method for preparing the charge storage and injection enhancement layer 4, the charge storage and injection enhancement layer 4 such as the deposited iridium oxide layer or conductive polymer layer can be effectively combined on the three-dimensional platinum nano-layer 3, and make the The above-mentioned charge storage and injection enhancement layer 4 is formed along the textured surface 31 structure of the three-dimensional platinum nano-layer 3, that is, the composite function formed by the three-dimensional platinum nano-layer 3 and the charge storage and injection enhancement layer 4 as shown in FIG. 4 is formed. layer, so as to effectively reduce the impedance of the prepared microelectrodes, increase the electrochemical properties such as charge storage capacity and charge injection ability, and ensure that the prepared microelectrodes have good biocompatibility and long-term stability such as mechanical stability and electrochemical stability. Thereby improving the electrical stimulation efficiency of the prepared microelectrode.

In a further embodiment, before the step of sequentially preparing the three-dimensional platinum nano-layer 3 and the charge storage and injection enhancement layer 4 on the outer surface of the micro-electrode unit 2, a step of cleaning the surface of the micro-electrode unit is also included. In one embodiment, the above cleaning method is:

Place the microelectrode unit 2 of the microelectrode described above in an acetone/ethanol solution for ultrasonic cleaning for 10 to 30 minutes, and then perform cyclic voltammetry scanning treatment in a 0.5M H ₂ SO ₄ solution (passing nitrogen to remove oxygen in the solution, -0.2V～1.2Vvs Ag/AgCl, 100～300mV/s, 10～50 cycles), to ensure that the surface of the microelectrode array is thoroughly cleaned.

Therefore, the above microelectrode preparation method can control and optimize the structural shape and size of the prepared three-dimensional platinum nanolayer 3 and the injection enhancement layer 4 by controlling the process conditions for preparing the three-dimensional platinum nanolayer 3 and the charge storage and injection enhancement layer 4 , so that the outer surface of the composite functional layer composed of the three-dimensional platinum nano-layer 3 and the charge storage and injection enhancement layer 4 is shown in FIG. 4 . Therefore, the prepared microelectrode has a large surface area, effectively reduces the prepared microelectrode impedance, increases the electrochemical performance such as charge storage capacity and charge injection ability, and ensures that the prepared microelectrode has good biocompatibility and such as mechanical stability and Long-term stability such as electrochemical stability, thereby improving the electrical stimulation efficiency of the prepared microelectrodes. In addition, each step of the microelectrode preparation method can be effectively controlled, thereby ensuring that the prepared microelectrode has stable performance, high efficiency, and can be industrialized.

In another aspect, on the basis of the above-mentioned microelectrode and its preparation method, the embodiment of the present invention also provides the application method of the above-mentioned microelectrode. As mentioned above, the microelectrode is also combined with a composite functional layer structure formed by a three-dimensional platinum nano-layer 3 and a charge storage and injection enhancement layer 4 on the surface of its microelectrode unit 2, thus endowing the above-mentioned microelectrode Electrochemical properties such as low impedance, high charge storage capacity and charge injection capacity, good working stability, and high electrical stimulation efficiency, therefore, effectively expand the application range of the above-mentioned microelectrode, as mentioned above The microelectrode can be selected as a stimulating electrode or a recording electrode according to the purpose, and can also be selected according to the different microscopic shapes of the composite functional layer formed by the three-dimensional platinum nanolayer 3 and the charge storage and injection enhancement layer 4 (such as platinum nanocone, platinum nanoflower etc.) selected as drug loading and other purposes. Therefore, in one embodiment, the microelectrodes described above can be used in sensors, wearable devices or implantable devices (such as in vivo pH measurement, ion analysis, neural prosthesis, neural stimulation/recording), etc., Thereby improving the sensitivity of the corresponding device and improving the accuracy.

Now in conjunction with specific examples, the microelectrode of the present invention and its preparation method will be further described in detail.

Example 1

This embodiment provides a microelectrode and a preparation method thereof. The structure of the microelectrodes is as shown in Figures 1-4, which includes a substrate 1 and a platinum microelectrode array 2 arranged on the substrate 1, and a three-dimensional platinum nanolayer 3 is also combined on the outer surface of the platinum microelectrode array 2, Also be combined with iridium oxide layer 4 on the outer surface of described three-dimensional platinum nano-layer 3, wherein, described three-dimensional platinum nano-layer 3 contains the suede 31 that distributes some platinum nano-cones, and described iridium oxide layer 4 is combined on the described Suede 31 on.

The preparation method of the microelectrode in this embodiment is as follows:

S11. Clean the platinum microelectrode array 2 contained in the microelectrode: place the microelectrode array 2 in an acetone/ethanol solution for ultrasonic cleaning for 10 to 30 minutes, and then process it in a 0.5M H ₂ SO ₄ solution by cyclic voltammetry scanning (generally Nitrogen removes the oxygen in the solution, -0.2V～1.2V vs Ag/AgCl, 100～300mV/s, 10～50 cycles), to ensure that the surface of the microelectrode array is thoroughly cleaned;

S12. Deposit a three-dimensional platinum nanolayer 3 containing a number of platinum nanocone suedes 31: deposit a plating solution containing a composite platinum salt on the outer surface of the microelectrode unit 2 of the microelectrode after cleaning by means of constant potential deposition. The three-dimensional platinum nanolayer 3 of the platinum nanocone textured surface 31; wherein, the relevant process conditions of the constant potential deposition method are as follows:

The voltage of constant potential deposition is -0.7V, the deposition time is 10-30min, and the pH of the plating solution during deposition is ~7.8;

The formula of the plating solution containing composite platinum salt is as follows:

At room temperature, add 10mmol of ammonium chloroplatinate and 5mmol of potassium chloroplatinate into a container containing 1L of distilled water and stir evenly, add an appropriate amount of disodium hydrogen phosphate and sodium dihydrogen phosphate compound salt to adjust the pH of the solution to ~7.8, A composite platinum salt plating solution is obtained.

S13. Deposit iridium oxide slowly on the suede surface 31 of the three-dimensional platinum nano-layer 3: deposit the iridium oxide layer 4 on the suede surface 31 by means of constant potential deposition with the plating solution containing iridium salt; wherein, the constant potential deposition mode The relevant process conditions are as follows:

The voltage of constant potential deposition is 0.35V, the deposition time is 40-60min, and the pH of the plating solution is ~11 during deposition;

The formula of the plating solution containing iridium salt is as follows:

At room temperature, add 2mmol of chloroiridic acid, 5mL of sodium peroxide and 3mmol of acetic acid into a container containing 1L of distilled water and stir evenly, adjust the pH of the solution to ~11 to obtain an iridium salt plating solution.

The three-dimensional platinum nanolayer 3 prepared in step S12 in the present embodiment 1 is observed by SEM, and the SEM image of the suede 31 is as shown in Figure 3, and there are many platinum nanometer layers growing on its surface. cone. It is determined that the height of the platinum nano cones is 50-600nm, and the distribution density is 50-400/μm ² .

The outer surface of the iridium oxide layer 4 prepared in step S13 in the present embodiment 1 was observed by SEM. As shown in FIG. The iridium oxide layer 4 is formed on the surface. After measurement, the iridium oxide particles have a diameter of 50-500nm and a thickness of 5nm-600nm. There is no obvious crack in the iridium oxide layer 4. Therefore, the iridium oxide layer 4 is deposited on the suede 31 surface to avoid It prevents iridium oxide from being too dense to cause cracks during the deposition process and fails; at the same time, the bonding force of the composite coating is also effectively improved, which helps to improve the long-term stability of the coating.

Example 2

This embodiment provides a microelectrode and a preparation method thereof, and the specific steps are as follows:

S21. Clean the platinum microelectrode array 2 contained in the microelectrode: place the microelectrode array 2 in an acetone/ethanol solution and ultrasonically clean it for 10 to 30 minutes, then scan it by cyclic voltammetry in a 0.5M H ₂ SO ₄ solution for 10 to 50 minutes. circle to ensure that the surface of the microelectrode array is thoroughly cleaned;

S22. Deposit a three-dimensional platinum nanolayer 3 containing a number of platinum nanocone suedes 31: deposit a plating solution containing a composite platinum salt on the outer surface of the microelectrode unit 2 of the cleaned microelectrode by constant current deposition. The three-dimensional platinum nanolayer 3 of the platinum nanocone textured surface 31; wherein, the relevant process conditions of the constant current deposition method are as follows:

The current of constant current deposition is -1.5μA, the deposition time is 10-30min, and the pH of the plating solution during deposition is ~7.8;

The formula of the plating solution containing composite platinum salt is as follows:

At room temperature, add 20mmol of ammonium chloroplatinate and 5mmol of platinum nitrate into a container containing 1L of distilled water and stir evenly, add an appropriate amount of sodium dihydrogen phosphate and disodium hydrogen phosphate compound salt to adjust the pH of the solution to ~7.8 to obtain a compound Platinum salt bath;

S23. Slowly deposit iridium oxide on the suede 31 of the three-dimensional platinum nano-layer 3: deposit the iridium oxide layer 4 on the suede 31 by means of constant current deposition with the plating solution containing iridium salt; wherein, the constant current deposition mode The relevant process conditions are as follows:

The voltage of constant current deposition is 0.05μA, the deposition time is 40-60min, and the pH of the plating solution is ~11 during deposition;

The formula of the plating solution containing iridium salt is as follows:

At room temperature, respectively add 5 mmol of potassium chloroiridate and 100 mmol of oxalic acid into a container containing 1 L of distilled water and stir evenly, adjust the pH of the solution to ~11 to obtain an iridium salt plating solution.

The height of the platinum nanocones in this embodiment is 50-600 nm, and the distribution density is 50-400/μm ² . Subsequently, iridium oxide particles are uniformly deposited on the suede surface 31 of the three-dimensional platinum nano-layer 3 at a slower deposition rate to form an iridium oxide layer 4, the diameter of the iridium oxide particles is 50-500nm, and the thickness is 5nm-600nm.

Example 3

This embodiment provides a microelectrode and a preparation method thereof, and the specific steps are as follows:

S31. Cleaning the platinum microelectrode array 2 contained in the microelectrode to ensure that the surface of the microelectrode array is thoroughly cleaned;

S32. Depositing a three-dimensional platinum nanolayer 3 containing a number of platinum nanocone suedes 31: depositing a plating solution containing a composite platinum salt on the outer surface of the microelectrode unit 2 of the cleaned microelectrode by pulse electrodeposition. The three-dimensional platinum nanolayer 3 of the platinum nanocone textured surface 31; wherein, the relevant process conditions of the pulse electrodeposition method are as follows:

The potential of pulse electrodeposition is -0.35V, the on-off ratio is 10ms:500ms, 1000 cycles, and the pH of the plating solution is ~7.8 during deposition;

The formula of the plating solution containing composite platinum salt is as follows:

At room temperature, add 5mmol of platinum sulfate and 10mmol of sodium chloroplatinate into a container containing 1L of distilled water and stir evenly, add 20mmol of organic or inorganic ammonium salt additives, and add appropriate amount of sodium dihydrogen phosphate and disodium hydrogen phosphate The compound salt adjusts the pH of the solution to ~7.8 to obtain a compound platinum salt plating solution;

S33. Deposit iridium oxide slowly on the suede surface 31 of the three-dimensional platinum nano-layer 3: deposit the iridium oxide layer 4 on the suede surface 31 with the plating solution containing iridium salt by pulse electrodeposition; wherein, the pulse electrodeposition method The relevant process conditions are as follows:

The voltage of pulse electrodeposition is 0.35V, the on-off ratio is 10ms:500ms, 1000 cycles, and the pH of the plating solution is ~11 during deposition;

The formula of the plating solution containing iridium salt is as follows:

At room temperature, add 5mmol of sodium chloroiridate, 15mL of sodium peroxide and 10mmol of citric acid into a container containing 1L of distilled water and stir evenly, adjust the pH of the solution to ~11 to obtain an iridium salt plating solution.

The height of the platinum nanocones in this embodiment is 50-600 nm, and the distribution density is 50-400/μm ² . Subsequently, iridium oxide particles are uniformly deposited on the suede surface 31 of the three-dimensional platinum nano-layer 3 at a slower deposition rate to form an iridium oxide layer 4, the diameter of the iridium oxide particles is 50-500nm, and the thickness is 5nm-600nm.

Example 4

This embodiment provides a microelectrode and a preparation method thereof, and the specific steps are as follows:

S31. Cleaning the platinum microelectrode array 2 contained in the microelectrode to ensure that the surface of the microelectrode array is thoroughly cleaned;

S32. Deposit a three-dimensional platinum nanolayer 3 containing a number of platinum nanocone suedes 31: deposit a plating solution containing a composite platinum salt on the outer surface of the microelectrode unit 2 of the cleaned microelectrode by a constant potential deposition method containing a number of The three-dimensional platinum nanolayer 3 of the platinum nanocone textured surface 31; wherein, the relevant process conditions of the constant potential deposition method are as follows:

The potential of constant potential deposition is -0.5V, the deposition time is 30-60min, and the pH of the plating solution during deposition is ~7.8;

The formula of the plating solution containing composite platinum salt is as follows:

At room temperature, add 2mmol of platinum nitrate and 15mmol of potassium chloroplatinate into a container containing 1L of distilled water and stir evenly, add 15mmol of organic or inorganic ammonium salt additives, and add an appropriate amount of sodium dihydrogen phosphate and disodium hydrogen phosphate The compound salt adjusts the pH of the solution to ~7.8 to obtain a compound platinum salt plating solution;

S33. Deposit iridium oxide slowly on the suede surface 31 of the three-dimensional platinum nano-layer 3: deposit the iridium oxide layer 4 on the suede surface 31 using the plating solution containing iridium salt by cyclic voltammetry deposition; wherein, cyclic voltammetry deposition The relevant process conditions of the method are as follows:

The voltage of cyclic voltammetry deposition is 0.01V ~ 0.65V, and the cycle is 50 ~ 500 cycles, and the pH of the plating solution is ~ 11 during deposition;

The formula of the plating solution containing iridium salt is as follows:

At room temperature, add 2mmol of sodium chloroiridate, 10mL of hydrogen peroxide and 8mmol of acetic acid into a container containing 1L of distilled water and stir evenly, adjust the pH of the solution to ~11 to obtain an iridium salt plating solution.

The height of the platinum nanocones in this embodiment is 50-600 nm, and the distribution density is 50-400/μm ² . Subsequently, iridium oxide particles are uniformly deposited on the suede surface 31 of the three-dimensional platinum nano-layer 3 at a slower deposition rate to form an iridium oxide layer 4, the diameter of the iridium oxide particles is 50-500nm, and the thickness is 5nm-600nm.

Comparative example 1

The iridium oxide layer 4 is directly deposited on the surface of the microelectrode unit 2 of the microelectrode described in Example 1 (after the cleaning treatment as in Step S11 of Example 1) using the same method and process conditions as in Step S13 of Example 1.

The iridium oxide layer 4 deposited directly on the surface of the microelectrode unit 2 in Comparative Example 1 was observed by SEM. As shown in FIG. The iridium oxide layer 4 is prone to cracks, which seriously affects the long-term stability of the coating. In fact, the bonding force between the single iridium oxide coating layer 4 and the unmodified platinum microelectrode unit 2 is not good, that is, the bonding strength between the iridium oxide layer 4 and the microelectrode unit 2 is not high.

Comparative example 2

Directly on the surface of the microelectrode unit 2 of the microelectrode as described in Example 1 (through the cleaning process as in Example 1 step S11), the method and process conditions as in Example 1 step S12 are deposited on the surface containing a number of platinum nano-cone suede 31 distributed. 3D platinum nanolayers 3 . That is, it is not like in Example 1 to continue to deposit the iridium oxide coating 4 on the surface of the three-dimensional platinum nano-layer 3 .

Comparative example 3

Embodiment 1 provides a microelectrode comprising a substrate 1 and a platinum microelectrode array 2 disposed on the substrate 1 . That is, it is not as in Example 1 that the three-dimensional platinum nano-layer 3 and the iridium oxide coating 4 are successively deposited on the surface of the platinum microelectrode array 2 .

Related performance tests:

The microelectrodes provided in the above-mentioned Example 1 and Comparative Examples 1-3 were respectively subjected to the following experimental tests of related properties:

1. Impedance performance test: The test results are shown in Figure 6. As can be seen from Figure 6, the impedance of a single platinum nanocone coating (the microelectrode provided in Comparative Example 1) reduces >80% compared to the unmodified electrode (platinum substrate, the microelectrode provided in Comparative Example 3), while the iridium oxide/platinum nanocone The composite coating (the microelectrode provided in Example 1) was reduced by >95% compared to the unmodified electrode (platinum substrate, the microelectrode provided in Comparative Example 3). The reduction of the impedance value greatly reduces the energy consumption of the microelectrode array implantation stimulation in the later stage.

2. Cyclic voltammetry (CV) test: the test results are shown in FIG. 7 . As can be seen from Fig. 6, the CV area of iridium oxide/platinum nano cone composite coating (the microelectrode that embodiment 1 provides) is obviously greater than other (comparative examples 1-3) any coating, the charge storage of iridium oxide/platinum nano cone composite coating Compared with the microelectrode provided by Comparative Example 3, the capacity is increased by at least 6 times.

3. Cyclic voltammetry (CV) test of the microelectrode provided in Example 1 before and after electrical stimulation: the microelectrode provided by the embodiment is cycled at 1 hour, 24 hours, 72 hours and 96 hours of electrical stimulation respectively Volt-ampere (CV) test, the test results are shown in Figure 8. As can be seen from Figure 8, although the CV area of the iridium oxide/platinum nanocone composite coating provided by Example 1 decreases with the prolongation of the electrical stimulation time, even after 96 hours of electrical stimulation, its CV area is still far greater than that of Compared with the microelectrode of Example 3, the charge storage capacity is still more than 5 times higher.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (10)

1. a kind of microelectrode, comprise substrate and be arranged on the microelectrode unit on described substrate, it is characterized in that: also be combined with three-dimensional platinum nano-layer on described micro-electrode unit outer surface, on described three-dimensional platinum nano-layer outer surface A charge storage and injection enhancement layer is also combined, wherein the three-dimensional platinum nanolayer contains a textured surface with several platinum nanocones or platinum nanoflowers, and the charge storage and injection enhancement layer is combined on the textured surface. 2. The microelectrode according to claim 1, characterized in that: the height of the platinum nanocones or platinum nanoflowers is 50nm-800nm, and the bottom diameter is 50nm-500nm, and/or The distribution density of the platinum nanocones or platinum nanoflowers is 25-400/μm ² , and/or The charge storage and injection enhancement layer has a thickness of 5nm-600nm. 3. The microelectrode according to claim 1 or 2, characterized in that: the material of the charge storage and injection enhancement layer is iridium oxide or a conductive polymer; wherein, the material of the charge storage and injection enhancement layer is iridium oxide , the charge storage and injection enhancement layer is deposited one by one on the suede surface of the three-dimensional platinum nanolayer by iridium oxide nanoparticles, stacked to form a layer; and/or The micro-electrode unit is any one of a disk electrode, a ring electrode, a cylindrical electrode, a spherical electrode, a semi-spherical electrode, a strip electrode, an array electrode, and an interdigitated electrode. 4. A preparation method for a microelectrode, comprising the steps of: A three-dimensional platinum nanolayer and a charge storage and injection enhancement layer are sequentially prepared on the outer surface of the microelectrode unit arranged on the substrate; wherein, the three-dimensional platinum nanolayer contains a suede surface distributed with several platinum nanocones or platinum nanoflowers, and the The charge storage and injection enhancement layer is combined on the suede surface. 5. preparation method according to claim 4, is characterized in that: the method for described preparation three-dimensional platinum nano-layer is as follows: Depositing the three-dimensional platinum nano-layer on the outer surface of the microelectrode unit by means of constant potential deposition, constant current deposition, or pulse voltage deposition in the plating solution containing the composite platinum salt; and/or The method for preparing the charge storage and injection enhancement layer is as follows: The plating solution containing iridium salt adopts any mode of constant potential deposition, constant current deposition, pulse voltage deposition, pulse current deposition, and cyclic voltammetry to deposit an iridium oxide layer on the suede surface; or deposit the conductive polymer solution on A conductive polymer layer is formed on the suede. 6. The preparation method according to claim 4 or 5, characterized in that: in the step of preparing the three-dimensional platinum nano-layer, the potential of the constant potential deposition is -0.35V～-0.75V; The current of galvanic deposition is -0.25μA～-1.75μA; the voltage of said pulse deposition is -0.35V～-0.75V, and the on-off ratio is (2ms-100ms):(200ms-1000ms); said composite platinum salt Platinum salts in the plating solution include platinum chloride, ammonium hexachloroplatinate, potassium hexachloroplatinate, sodium hexachloroplatinate, chloroplatinic acid, platinum nitrate, platinum sulfate, potassium tetrachloroplatinate, ammonium tetrachloroplatinate At least two of them; the deposition time of any one of the constant potential deposition, constant current deposition, and pulse voltage deposition is 5 to 60 minutes, and the pH of the plating solution is ≥ 7; In the step of preparing the iridium oxide layer, the voltage of the constant potential deposition is 0.35V～0.65V; the current of the constant current deposition is 0.05μA～1.5μA; the voltage of the pulse deposition is 0.35V～0.65V V, the on-off ratio is (2ms-100ms): (200ms-1000ms); the cyclic voltammetry deposition voltage is 0.01V～0.8V, and the number of cycles is 20 circles～600 circles; the plating solution containing iridium salt The iridium salts in include at least one of iridium salts such as iridium chloride, chloroiridic acid, ammonium hexachloroiridate, potassium hexachloroiridate, sodium hexachloroiridate; the constant potential deposition, constant current deposition, pulse The deposition time of any method of voltage deposition is 5 to 60 minutes, and the pH of the deposition is ≥ 10; The conductive polymer is at least one of polypyrrole, polyaniline, polythiophene and polythiophene derivatives, and the thickness of the conductive polymer layer is 5nm-600nm. 7. preparation method according to claim 6, is characterized in that: also can add organic or inorganic ammonium salt additive in the described plating solution that contains composite platinum salt, wherein, with the described plating solution gross mass that contains composite platinum salt Based on 100%, the content of the composite platinum salt is 1-50%, and the content of the additive is 0-20%; and/or The plating solution containing iridium salt also contains weak acid or oxidizing agent and weak acid, wherein, based on the total mass of the plating solution containing iridium salt being 100%, the content of the iridium salt is 0.05-10%, and the oxidizing agent The content of the weak acid is 0-10%, and the content of the weak acid is 0.1-10%. 8. The preparation method according to claim 7, wherein the additive is one of organic or inorganic ammonium salts such as ethylenediamine dihydrochloride, ammonium chloride, ammonium sulfate, and ammonium nitrate. 9. preparation method according to claim 7 is characterized in that: described oxidizing agent is at least one in hydrogen peroxide, sodium peroxide, potassium peroxide, oxygen, ozone, and described weak acid is oxalic acid, citric acid, At least one of carbonic acid, acetic acid, formic acid, and benzoic acid. 10. The application of the microelectrode prepared according to claim 1-3 or by the preparation method described in any one of claims 4-10 in sensors, wearable devices or implantable devices.